Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

To the Editor,

We would like to thank you for your interest in our research and article and for some questions and comments through the Letter to the Editor. We would like to respond to them.

Firstly, we applied a mixture of EV and hydrogel inside the full thickness skin defect wound and dressed using Tegaderm (3M, St. Paul, MN, USA) it. Additionally, we used male Sprague-Dowley rats (Crl:CD(SD), 16 wks) in our study, and did not measure their weight, but most of them were about the same size.

Secondly, we measured the positive area as image J on the tissue slide and compared the differences between groups by displaying the results on Fig 4, 6, and 8. In addition, we have confirmed the expression of CD31 and VEGF stimulating angiogenesis, which are mainly used for evaluating angiogenesis, and thank you for your recommendation.

Finally, further research will be conducted on how EVs separated from 3D-cultured PVCs have a better effect on wound healing than PVC-2D-EVs.